To improve the development of wireless communications technologies, a Long Term Evolution (LTE) project is set up by the 3rd Generation Partnership Project (3GPP). Multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) are the two most crucial technologies in the LTE project. In an actual LTE application scenario, a neighboring cell may interfere with user equipment (UE), and the interference may severely affect performance of demodulating data by the UE. In addition, in an MU-MIMO (multi-user MIMO) system, a specific scheduling mechanism may be used to select UEs that meet a requirement and group the UEs into a group, and antennas of multiple UEs in one group constitute a virtual multi-antenna array. A base station and multiple UEs in the group may send and receive data on a same time-frequency resource, the group of UEs are referred to as paired UEs, and interference may exist between the paired UEs. Using FIG. 1 as an example, a serving base station 11 may be an eNodeB, and provides a service for multiple UEs, such as UE 121, UE 122, and UE 123, in a serving cell 110. The UE 121 is close to an edge of the cell 110, and is subjected to interference from a cell 130 formed by another base station 13, and this is also called inter-cell interference, that is, a communications link 131 between the another base station 13 and the UE 121 is an interference link of a communications link in between the serving base station 11 and the UE 121. The UE 122 and the UE 123 are paired UEs, when the serving base station 11 performs MU-MIMO transmission to the UE 122 and the UE 123, interference may also exist between the UE 122 and the UE 123, that is, a communications link 112 between the UE 122 and the serving base station 11 and a communications link 113 between the UE 123 and the serving base station 11 interfere with each other. A link may also be considered as a channel.
The LTE project defines a standard receiver for rejecting interference in Release 11 (Release 11), for example, an interference rejection combining (IRC) receiver. However, a capability of rejecting inter-cell interference by the IRC is limited, and the IRC cannot reject interference between UEs well. Therefore, in LTE, a receiver having a stronger capability is defined in Release 12, for example, a symbol level interference cancellation (SLIC) receiver and a maximum likelihood (ML) receiver, to achieve a better interference rejection effect.
In an LTE system, a serving base station 11 may schedule appropriate radio resources, a modulation and coding scheme (MCS), Precoding Matrix Indicator (PMI), and a Rank Index (RI) for any UE, such as UE 121, according to channel state information (CSI) reported by the UE 121, to ensure normal communication of the UE 121. The UE 121 may calculate the CSI according to a minimum mean square error (MMSE) criterion, for which a received signal-to-noise ratio of the UE 121 needs to be calculated first, that is, a ratio of a valid signal to interference, the CSI is determined based on the signal-to-noise ratio, and the CSI is fed back to the base station 11. However, in a process of calculating the signal-to-noise ratio, the UE 121 does not consider inter-cell interference or interference between UEs; as a result, an obtained signal-to-noise ratio or obtained CSI is not accurate. Particularly, when the SLIC receiver or the ML receiver is used in the UE 121, the signal-to-noise ratio obtained by using the MMSE by means of calculation often cannot reflect an actual channel state of the UE, and therefore, inaccurate CSI is further obtained.